JP5909071B2 - Centrifugal rotator design method, centrifugal rotator manufacturing method, and centrifugal rotator design system - Google Patents

Description

  The present invention relates to a centrifugal rotator design method, a centrifugal rotator manufacturing method, and a centrifugal rotator design system that can prevent the occurrence of resonance of a rotating shaft while satisfying necessary performance.

  In a centrifugal rotating machine such as a centrifugal compressor and a centrifugal pump, a plurality of impellers are provided on a rotating shaft along the axial direction of the rotating shaft. The impeller includes a substantially disk-shaped disk attached to the rotating shaft, and a plurality of blades provided on the front surface of the disk along the circumferential direction and extending from the inner circumferential side toward the outer circumferential side (see, for example, Patent Document 1). ). Further, there is a case where a substantially disk-shaped shroud is attached to the edge opposite to the edge attached to the disk of the blade, facing the front surface of the disk. Generally, an impeller having such a shroud is a closed impeller. An impeller without a shroud is called an open impeller. The front surface of the disk is formed along the axial direction on the inner peripheral side, and is curved so as to extend along the radial direction toward the outer peripheral side. Then, a plurality of spaces formed by the impellers adjacent to such a front surface are used as fluid flow paths. For example, in a centrifugal compressor, the impeller rotating with the rotating shaft along the axial direction on the inner peripheral side. The fluid flowing into the flow path is discharged to the outer peripheral side while being compressed by the centrifugal force acting by the rotation of the impeller. Here, the number of stages of the impeller and the shape of the impeller are different for each centrifugal rotator due to a difference in required performance. In particular, in the case of a compressor, the gas density increases as it goes downstream in the gas flow direction, thereby reducing the volume flow rate. Therefore, impellers having different shapes are arranged at each stage.

  By the way, when designing a centrifugal rotating machine having such a multi-stage impeller, resonance of the rotating shaft becomes a problem. That is, when the number of impeller stages is large, the axial length of the rotating shaft is increased accordingly, so that the natural frequency of the rotating shaft is lowered. And when the natural frequency of this rotating shaft becomes a magnitude | size close | similar to the rotational speed of a centrifugal rotator, resonance generate | occur | produces in a rotating shaft.

  In order to suppress such resonance of the rotating shaft, it is necessary to increase the natural frequency of the rotating shaft and keep it away from the rotating speed of the centrifugal rotating machine. It is necessary to increase the diameter. As a means for shortening the shaft length of the rotating shaft or increasing the shaft diameter, there are other methods such as a method of shortening the shaft length of the rotating shaft by narrowing the space on the upstream side or downstream side of the impeller, There is a way to change to the type of. However, there are many cases in which resonance of the rotating shaft cannot be sufficiently suppressed even by these methods. Therefore, in such a case, a method of shortening the axial length of each rotating shaft by dividing the rotating shaft and the casing that accommodates the rotating shaft has been conventionally used. In addition, a method of shortening the shaft length of the rotating shaft or increasing the shaft diameter by developing an impeller having a new shape including a blade has been conventionally used.

JP 2010-159858 A

  However, the conventional centrifugal rotator design method in which the rotating shaft and the casing are divided has a problem that the manufacturing cost and installation space increase due to an increase in the number of centrifugal rotators. In addition, the conventional centrifugal rotator design method that develops impellers with new shapes including blades makes it difficult to design the aerodynamics of the blades, and it is necessary to develop many impellers with different volume flow rates. There was a problem of being bulky.

  The present invention has been made in consideration of such circumstances, and its purpose is to achieve the required performance by changing the structure on the inner peripheral side of the blade without changing the structure of the blade. It is an object to provide a method and a system for designing a centrifugal rotating machine that satisfies the above requirements and does not cause resonance of a rotating shaft at low cost.

  In order to achieve the above object, the present invention employs the following means. That is, the centrifugal rotator design method according to the present invention is a design method of a centrifugal rotator provided with a rotating shaft and a plurality of impellers provided in the rotating shaft along the axial direction. Structural specification determination step for determining the structure specification including the impeller type of each stage in the centrifugal rotator and the rotational speed of the centrifugal rotator so as to satisfy the weight flow rate and the inlet / outlet pressure ratio, and the structure determined in the structural specification determination step A shaft natural frequency calculating step for calculating a shaft natural frequency of the centrifugal rotator in the specification, a shaft natural frequency of the centrifugal rotator calculated in the shaft natural frequency calculating step, and a structure specification determining step. A resonance determination step for determining whether or not to resonate based on the determined rotational speed of the centrifugal rotator, and at least one stage when it is determined to resonate in the resonance determination step With respect to the impeller, a boss ratio which is a value obtained by dividing the minimum diameter of the disk constituting the impeller by the maximum diameter of the disk is within a boss ratio setting range obtained in advance corresponding to the model of the impeller. A boss ratio changing step for setting the boss ratio to a value higher than the initial value. When the boss ratio is set in the boss ratio changing step, the impeller for which the boss ratio is set in the structural specification determining step Without changing the structure of the blade constituting the structure, change the structure on the inner peripheral side from the blade to change the boss ratio, determine the structural specifications and the centrifugal rotator rotational speed again, A natural frequency calculation step and a resonance determination step are executed.

  According to such a method, since the structure of a blade that requires time and cost for development is not changed, the time and cost required for designing a centrifugal rotating machine can be reduced. Moreover, since the structural specifications are determined after changing the boss ratio, the centrifugal rotator after the boss ratio change satisfies the weight flow rate and the inlet / outlet pressure ratio acquired in advance. Further, since the natural frequency calculation step and the resonance determination step are executed thereafter, it is confirmed that no resonance occurs.

In the centrifugal rotating machine design method according to the present invention, the structural specification determined in the structural specification determining step further includes the number of impeller stages and the maximum diameter of the disk in each stage.

According to such a method, it is possible to design a centrifugal rotating machine having an appropriate structure specification including the number of impeller stages and the maximum diameter of the disk of each stage.

  In the centrifugal rotator design method according to the present invention, the boss ratio changing step is executed when it is determined that the resonance determining step is repeated a predetermined number of times to resonate. .

  According to such a method, the boss ratio is not changed when a centrifugal rotator that satisfies the required performance and does not generate resonance can be designed only by changing the structural specifications, so the time and labor required for designing the centrifugal rotator are not changed. Can be minimized.

  In the design method of the centrifugal rotating machine according to the present invention, the initial value of the boss ratio is set to a minimum boss ratio in the structural specification determination step, and the boss ratio setting range in the boss ratio change step is the minimum value. It is defined as a range from a boss ratio to a predetermined maximum boss ratio.

  According to such a method, it is possible to design a centrifugal rotator with higher performance by minimizing the boss ratio at the time of initial design, and it is impossible to prevent resonance from occurring at the time of initial design. In addition, since the change width of the boss ratio can be secured sufficiently large, it is possible to easily select a condition in which resonance does not occur within a range that satisfies the performance.

  The centrifugal rotator manufacturing method according to the present invention includes the above-described centrifugal rotator design method, the design process of designing the structure of the centrifugal rotator, and the structural specifications designed in the design process, A member manufacturing process for manufacturing each centrifugal rotator member including a rotating shaft in a rotating machine, an impeller attached to the rotating shaft, and a casing that rotatably supports the rotating shaft while accommodating the impeller, and a member manufacturing process. And a member assembling step for assembling the centrifugal rotator member.

  According to such a manufacturing method, the centrifugal rotator can be manufactured by manufacturing the centrifugal rotator members constituting the centrifugal rotator and assembling them.

In addition, the design system of the centrifugal rotator according to the present invention determines the structural specifications including the impeller type of each stage in the centrifugal rotator and the rotational speed of the centrifugal rotator so as to satisfy the previously obtained weight flow rate and inlet / outlet pressure ratio. A structural specification determining means, a shaft natural frequency of the centrifugal rotator calculated from the structural specification determined by the structural specification determining means, and the centrifugal rotator rotational speed determined by the structural specification determining means. A resonance determining means for determining whether or not to resonate, and a boss ratio obtained in advance corresponding to the type of the impeller for at least one stage of the impeller when it is determined by the resonance determining means to resonate among the set range, the minimum diameter of the disk constituting the impeller set the boss ratio is a value obtained by dividing the maximum diameter of the disk to a value higher than the initial value, to output to the structure specification determining means Boss ratio changing means, and when the boss ratio is output from the boss ratio changing means, the structural specification determining means changes the structure of the blades constituting the impeller for the impeller with the boss ratio set. Without changing, the structure on the inner peripheral side of the blade is changed to change the structure so that the boss ratio is obtained, and the structural specification and the rotational speed of the centrifugal rotator are determined again. It is characterized by determining whether to do.

  According to such a configuration, since the structure of the blade that requires time and cost for development is not changed, the time and cost required for designing the centrifugal rotating machine can be reduced. Further, after the boss ratio changing means changes the boss ratio, the structural specification determining means determines the structural specifications, so that the centrifugal rotator after the boss ratio change satisfies the previously obtained weight flow rate and inlet / outlet pressure ratio. Further, after that, since the resonance determining means determines whether or not it resonates with the calculation of the natural frequency, it is confirmed that no resonance occurs.

According to the centrifugal rotator design method and the centrifugal rotator design system according to the present invention, the required performance can be obtained by changing the structure on the inner peripheral side of the blade without changing the structure of the blade. It is possible to design a centrifugal rotating machine that satisfies the requirements and does not cause resonance of the rotating shaft at a low cost.
Moreover, according to the manufacturing method of the centrifugal rotating machine which concerns on this invention, the centrifugal rotating machine which satisfy | fills desired performance can be manufactured at low cost.

It is a schematic sectional drawing which shows the centrifugal compressor which concerns on embodiment of this invention. It is a block diagram which shows the function structure of the design system of the centrifugal compressor which concerns on embodiment of this invention. It is a figure which shows an example of the table which a memory | storage part stores. It is a flowchart which shows the flow of a process in a control part. It is the graph which showed the influence which the boss ratio of an impeller has on the performance of a centrifugal compressor, (a) shows the influence which the boss ratio has on efficiency ηi, and (b) shows the influence which the boss ratio has on the pressure coefficient μi. Show.

[Configuration of centrifugal compressor]
Embodiments of the present invention will be described below with reference to the drawings. First, a configuration of a centrifugal rotator designed by a centrifugal rotator design method and a centrifugal rotator design system according to an embodiment of the present invention will be described. In the present embodiment, a centrifugal compressor will be described as an example of a centrifugal rotating machine according to the present invention. FIG. 1 is a schematic cross-sectional view showing a centrifugal compressor 1 according to an embodiment of the present invention. The centrifugal compressor 1 includes a rotor 2 disposed along the axis L and a casing 3 that accommodates the rotor 2.

(Rotor)
As shown in FIG. 1, the rotor 2 includes a rotating shaft 21 whose driving side end is rotationally driven by a motor or the like (not shown), and a plurality of impellers fixed to the axial center of the rotating shaft 21 at predetermined intervals. 22.

  The impeller 22 plays a role of compressing gas using centrifugal force. As shown in FIG. 1, the impeller 22 includes a disk-shaped disk 221 and a plurality of blades 222 provided so as to protrude from the surface of the disk 221. Among these, the disk 221 is formed in a substantially circular shape when viewed in the axial direction, and is provided with a boss portion 221a whose central portion protrudes toward one side in the axial direction. Thereby, the surface on one side in the axial direction of the disk 221 is curved so as to go from the radial direction to the axial direction from the outer peripheral side toward the inner peripheral side. In the present invention, the maximum diameter of the disk 221 is defined as “impeller outer diameter D2”, and the minimum diameter of the disk 221, that is, the diameter at the tip of the boss 221a is defined as “boss diameter Db”. The boss diameter Db / impeller outer diameter D2 is defined as the “boss ratio”.

  The impeller 22 configured as described above is housed inside the casing 3, and the rotary shaft 21 is inserted into and fixed to the center of the disk 221. Thereby, the impeller 22 rotates integrally with the rotating shaft 21 as the rotating shaft 21 rotates. And the clearance gap between the some blades 222 which comprise the impeller 22 is comprised as the flow path 4 through which gas distribute | circulates. In the present embodiment, six stages of impellers 22 are provided at predetermined intervals along the axial direction of the rotating shaft 21, but the number of stages of the impellers 22 is not limited to this, and the design can be changed as appropriate.

(casing)
As shown in FIG. 1, the casing 3 includes a casing body 31 having a substantially cylindrical shape and open at both ends, a thrust bearing 32 fixed to one end portion in the axial direction of the casing body 31, and a shaft of the casing body 31. A pair of journal bearings 33 fixed to both ends in the direction.

  The thrust bearing 32 plays a role of receiving the rotary shaft 21 in the axial direction. As shown in FIG. 1, the thrust bearing 32 is accommodated in a bearing case 34 attached to one end side of the casing body 31, and one axial end portion of the rotary shaft 21 is rotatable around the axis. It is supported in a slightly movable state in the axial direction.

  The journal bearing 33 serves to receive the rotary shaft 21 in the radial direction. As shown in FIG. 1, the pair of journal bearings 33 are provided so that one of them is fitted in a shaft insertion hole on one end side of the casing body 31 and the other is attached to the other end side of the casing body 31. Housed inside the case 35. The pair of journal bearings 33 respectively support both axial ends of the rotating shaft 21 so as to be rotatable about the axis.

[Centric compressor design system]
Next, the design system of the centrifugal compressor 1 that uses the design method of the centrifugal compressor 1 according to the embodiment of the present invention will be described. FIG. 2 is a block diagram showing a functional configuration of the design system of the centrifugal compressor 1 according to the embodiment of the present invention. The design system of the centrifugal compressor 1 includes a storage unit 11 including a ROM and a RAM, an input unit 12 including a keyboard and a mouse, a display unit 13 including a liquid crystal screen, and a control unit 14 including an MPU. It has.

  The storage unit 11 stores a plurality of pieces of record information related to the type of the centrifugal compressor 1 used in the past in a chemical plant or the like in a table format. FIG. 3 is a diagram illustrating an example of the table T stored in the storage unit 11. The table T includes the centrifugal compressor 1 type name, gas composition (Comp), inlet temperature (T1), inlet pressure (P1), gas flow rate (G), inlet / outlet pressure ratio (Pr), impeller stage number (Z ), Specification data such as the model of the impeller 22 at each stage, the rotational speed (N), the outer diameter (D2i) of the impeller 22 at each stage, and the like are stored in association with each other. The format in which the storage unit 11 stores type data is not limited to the table format, and any format that can be stored in association with each other can be used.

  The input unit 12 is configured so that a user can input information on performance required for the centrifugal compressor 1. Here, examples of data that can be input by the user include gas composition (Comp), inlet temperature (T1), inlet pressure (P1), gas mass flow rate (G), inlet / outlet pressure ratio (Pr), and the like.

  As shown in FIG. 2, the control unit 14 includes a compressor type determination unit 141, a structure specification determination unit 142, an inlet / outlet pressure ratio calculation unit 143, a performance determination unit 144, a CAD drawing unit 145, and an axis natural vibration. Number calculation means 146, resonance determination means 147, resonance determination frequency count means 148, boss ratio change frequency count means 149, boss ratio change means 150, shaft casing division means 151, and new impeller development means 152 Have. In the present specification, “CAD” means Computer Aided Design (computer-aided design).

  As shown in FIG. 2, the compressor type determining means 141 receives performance information required for the centrifugal compressor 1 from the input unit 12. The compressor type determination unit 141 receives a table T related to the type of the centrifugal compressor 1 from the storage unit 11. Then, the compressor type determining means 141 selects a compressor type that satisfies the required performance from the table T and outputs it to the structural specification determining means 142.

  As shown in FIG. 2, the structural specification determination unit 142 receives the compressor type selected as described above from the compressor type determination unit 141. In addition, the structural specification determining unit 142 is input from the performance determining unit 144 that the inlet / outlet pressure ratio (Pr) does not satisfy the required performance condition. Further, the structural specification determining unit 142 receives an input from the resonance determination number counting unit 148 that the number of times that the resonance determination has been made has not reached a predetermined n times. Further, the structural specification determining unit 142 receives an input from the shaft casing dividing unit 151 that the rotating shaft 21 and the casing 3 are divided. Further, the structural specification determining means 142 receives an input from the new impeller developing means 152 to develop the impeller 22 having a new shape.

  Then, as shown in FIG. 2, the structural specification determining means 142, based on the compressor type input from the compressor type determining means 141, the number of stages (Z) of the impeller 22, the model of the impeller 22 of each stage, the rotation The number (N) and the outer diameter (D2i) of each stage of the impeller 22 are determined as structural specifications and output to the inlet / outlet pressure ratio calculating means 143, respectively. Further, the structural specification determining means 142 outputs the structural specifications for each stage of the impeller 22 to the CAD drawing means 145. Further, the structural specification determining unit 142 outputs the determined rotational speed (N) of the centrifugal compressor 1 to the resonance determining unit 147.

  As shown in FIG. 2, the inlet / outlet pressure ratio calculating means 143 receives the number of stages (Z) of the impeller 22, the type of the impeller 22 of each stage, the number of revolutions (N), and each stage from the structural specification determining means 142. The outer diameter (D2i) of the impeller 22 is input. Then, the inlet / outlet pressure ratio calculating unit 143 outputs the calculated inlet / outlet pressure ratio (Pr) to the performance determining unit 144.

  As shown in FIG. 2, the performance judging means 144 receives the inlet / outlet pressure ratio (Pr) from the inlet / outlet pressure ratio calculating means 143 as described above. The performance determining unit 144 determines whether the inlet / outlet pressure ratio (Pr) input from the inlet / outlet pressure ratio calculating unit 143 satisfies the performance required for the centrifugal compressor 1. The performance determining unit 144 then outputs to the CAD drawing unit 145 that the centrifugal compressor 1 satisfies the required performance. In addition, the performance determination unit 144 outputs to the structural specification determination unit 142 that the centrifugal compressor 1 does not satisfy the required performance.

  As shown in FIG. 2, the CAD drawing means 145 receives the structural specifications for the impellers 22 at each stage from the structural specification determination means 142 as described above. In addition, the CAD drawing unit 145 receives an input from the performance determination unit 144 that the centrifugal compressor 1 satisfies the required performance as described above. Further, the CAD drawing unit 145 receives an input from the resonance determination unit 147 that resonance does not occur. The CAD drawing unit 145 receives a new boss ratio after the change from the boss ratio changing unit 150.

  Then, the CAD drawing means 145 outputs the drawn CAD drawing data to the shaft natural frequency calculation means 146 as shown in FIG. The CAD drawing means 145 outputs the drawn CAD drawing data to the display unit 13.

  As shown in FIG. 2, the shaft natural frequency calculation means 146 receives the created CAD drawing data from the CAD drawing means 145. Then, the shaft natural frequency calculating means 146 measures the dimensions of each part from this CAD drawing, and calculates the shaft natural frequency of the rotating shaft 21 based on this. Then, the shaft natural vibration calculating unit 146 outputs the calculated shaft natural frequency to the resonance determining unit 147.

  As shown in FIG. 2, the resonance determining unit 147 receives the shaft natural frequency of the rotating shaft 21 from the shaft natural vibration calculating unit 146. The resonance determination unit 147 receives the rotational speed (N) of the centrifugal compressor 1 from the structural specification determination unit 142. And the resonance determination means 147 determines whether resonance generate | occur | produces in the rotating shaft 21 based on both input. The resonance determination unit 147 outputs to the CAD drawing unit 145 that resonance does not occur. In addition, the resonance determination unit 147 outputs to the resonance determination frequency count unit 148 that determination has been made regarding the occurrence of resonance.

  As shown in FIG. 2, the resonance determination number counting means 148 receives an input from the resonance determination means 147 that determination has been made regarding the occurrence of resonance. Then, the resonance determination number counting means 148 increases the determination number by 1, and determines whether or not the number of times of performing the resonance determination has reached a predetermined n times. As a result, the resonance determination number counting unit 148 outputs to the structural specification determining unit 142 that the number of times of resonance determination has not reached n times. On the other hand, the resonance determination number counting means 148 outputs to the boss ratio change number counting means 149 that the number of times of performing resonance determination has reached n times.

  As shown in FIG. 2, the boss ratio change count counting means 149 receives an input from the resonance determination count counting means 148 that the number of times the resonance has been determined has reached n. Then, the boss ratio change number counting means 149 determines whether or not the number of times the boss ratio has been changed has reached a predetermined m times. As a result, the boss ratio change count counting means 149 outputs to the boss ratio change means 150 that the number of times of changing the boss ratio has not yet reached m times. On the other hand, the boss ratio change number counting means 149 outputs to the shaft casing dividing means 151 that the number of times of changing the boss ratio has reached m times.

  As shown in FIG. 2, the boss ratio changing means 150 receives an input from the boss ratio change frequency counting means 149 that the number of times of changing the boss ratio has not reached m times. Further, the boss ratio changing means 150 receives from the storage unit 11 a graph that holds the relationship between the flow coefficient (φi) of the impeller 22 and the efficiency (ηi) of the centrifugal compressor 1 for each model. Then, the boss ratio changing unit 150 outputs a new boss ratio after the change to the CAD drawing unit 145.

  As shown in FIG. 2, the shaft casing dividing means 151 receives from the boss ratio change count counting means 149 that the number of times of changing the boss ratio has reached m times. Further, the shaft casing dividing means 151 outputs to the structural specification determining means 142 that the rotating shaft 21 and the casing 3 have been divided.

  As shown in FIG. 2, the new impeller development unit 152 receives an input from the boss ratio change count counting unit 149 that the number of times of changing the boss ratio has reached m times. Further, the new impeller development means 152 outputs to the structural specification determination means 142 that the impeller 22 having a new shape is to be developed.

  In place of the CAD drawing unit 145 and the shaft natural frequency calculation unit 146 of the present embodiment, the user manually draws a CAD drawing based on the structure specification of the impeller 22 and measures each part of the CAD drawing. The shaft natural frequency may be calculated from the result.

  Further, instead of the compressor type determining means 141 of the present embodiment, the user manually acquires the information of the table T from the storage unit 11 and the performance information from the input unit 12 respectively, and the centrifugal compressor 1 based on the information. May be determined and input to the structural specification determining means 142.

  Next, the flow of processing executed in the control unit 14 according to the embodiment of the present invention will be described. FIG. 4 is a flowchart showing the flow of processing in the control unit 14. When the design process of the centrifugal compressor 1 is started, the control unit 14 shown in FIG. 2 first executes a structural specification determination step. This structural specification determination step determines the structural specifications of the impellers 22 of each stage constituting the centrifugal compressor 1 so as to satisfy the performance required for the centrifugal compressor 1 and the rotation of the centrifugal compressor 1. This is a step of determining the number (N).

  The structural specification determining step will be described in detail. First, the compressor type determining means 141 shown in FIG. 2 has the performance required for the centrifugal compressor 1 as gas weight flow rate (G), inlet / outlet pressure ratio (Pr), Information on the gas composition (Comp), the inlet temperature (T1), and the inlet pressure (P1) is acquired (S1). Here, the inlet / outlet pressure ratio (Pr) means the pressure ratio between the outlet portion and the inlet portion in the flow path 4. Then, the compressor type determination unit 141 determines the type of the centrifugal compressor 1 by referring to the table T held by the storage unit 11 shown in FIG. 2 according to the acquired information (S2). The table T is a table in which the results related to the shape of the impeller 22 are accumulated in the centrifugal compressor 1 used in the same type of chemical plant in the past.

  Next, the structure specification determining means 142 shown in FIG. 2 satisfies the required gas weight flow rate (G) and inlet / outlet pressure ratio (Pr) based on the type of the input centrifugal compressor 1. In this way, the structural specifications of the impellers 22 in each stage are provisionally determined, and the rotational speed (N) of the centrifugal compressor 1 is determined (S3). Here, the structural specification of the impeller 22 in the present embodiment means the number of stages (Z) of the impeller 22, the type of the impeller 22 of each stage, and the outer diameter (D2i) of the impeller 22 of each stage.

Next, the inlet / outlet pressure ratio calculating means 143 shown in FIG. 2 calculates the inlet / outlet pressure ratio (Pr) of the centrifugal compressor 1 based on the provisionally determined structure specification of each stage of the impeller 22 (S4). More specifically, the inlet / outlet pressure ratio calculating means 143 first calculates the inlet density (ρ1) of the first stage impeller 22 by the following equation (1) based on the following equation (1). In this equation (1), fρ means a predetermined function.
ρ1 = fρ (comp, P1, T1) (1)

Next, the inlet / outlet pressure ratio calculating means 143 calculates the inlet volume flow rate (Q1) of the first stage impeller 22 by substituting the calculated inlet density (ρ1) into the following equation (2).
Q1 = G / ρ1 Equation (2)

Further, the inlet / outlet pressure ratio calculating means 143 substitutes the number of revolutions (N) of the centrifugal compressor 1 and the outer diameter (D21) of the first stage impeller 22 into the following expression (3) to obtain the first stage The peripheral speed (U21) of the impeller 22 is calculated.
U21 = N / 60 · π · D21 Equation (3)

Then, the inlet / outlet pressure ratio calculating means 143 calculates the inlet volume flow rate (Q1) obtained by the equation (2), the peripheral speed (U21) obtained by the equation (3), and the outer diameter (D21) from the following equations (4). ) To calculate the flow coefficient (φ1) of the first stage impeller 22. In Expression (4), “D21 ^ 2” means the square of D21.
φ1 = Q1 / (π / 4 × D21 ^ 2 × U21) Equation (4)

  Next, the inlet / outlet pressure ratio calculation means 143 has a plurality of graphs that the storage unit 11 shown in FIG. 2 holds for each model regarding the relationship between the flow coefficient (φi) of the impeller 22 and the efficiency (ηi) of the centrifugal compressor 1. Then, a graph corresponding to the model of the first stage impeller 22 is selected. Here, FIG. 5 is a graph showing the influence of the boss ratio of the impeller 22 on the performance of the centrifugal compressor 1, wherein (a) shows the influence of the boss ratio on the efficiency ηi, and (b) shows the boss ratio. Shows the influence of the pressure factor on the pressure coefficient μi. The solid line in the figure indicates the case where the boss ratio is set to the minimum boss ratio, and the broken line indicates the case where the boss ratio is set to the maximum boss ratio. In the present embodiment, the boss ratio is set to the lowest boss ratio in the structural specification determination step. The inlet / outlet pressure ratio calculating means 143 determines the efficiency (η1) of the centrifugal compressor 1 by applying the flow coefficient (φ1) calculated by the equation (4) to the graph shown in FIG.

  Similarly, the inlet / outlet pressure ratio calculating means 143 has a plurality of storage units 11 shown in FIG. 2 that hold the relationship between the flow coefficient (φi) of the impeller 22 and the pressure coefficient (μi) of the centrifugal compressor 1 for each model. From the graph, a graph corresponding to the model of the first stage impeller 22 is selected. Here, FIG. 5B is a graph showing the relationship between the flow coefficient (φi) and the pressure coefficient (μi) selected as corresponding to the model of the first stage impeller 22. The solid line in the figure shows the case where the boss ratio is set to the lowest boss ratio, and the broken line shows the case where the boss ratio is set to the highest boss ratio. In the structural specification determination step, the boss ratio is The minimum boss ratio is set. The inlet / outlet pressure ratio calculating means 143 determines the pressure coefficient (μ1) of the centrifugal compressor 1 by applying the flow coefficient (φ1) calculated by the equation (4) to the selected graph.

Next, the inlet / outlet pressure ratio calculation means 143 substitutes the peripheral speed (U21) obtained by the equation (3) and the pressure coefficient (μ1) determined from the graph of FIG. 5B into the following equation (5), respectively. Thus, the head (H1) of the first stage impeller 22 is calculated. In Equation (5), “U21 ^ 2” means the square of U21.
H1 = U21 ^ 2 / g × μ1 Equation (5)

Next, the inlet / outlet pressure ratio calculating means 143 substitutes the efficiency (η1) determined from the head (H1) obtained by the equation (5) and the graph of FIG. 5A into the following equation (6), respectively. Thus, the pressure ratio (Pr1) of the first stage impeller 22 is calculated. In this equation (6), fρ means a predetermined function.
Pr1 = fρ (comp, P1, T1, H1, η1) (6)

Further, the inlet / outlet pressure ratio calculating means 143 substitutes the efficiency (η1) determined from the head (H1) obtained by the equation (5) and the graph of FIG. 2 (a) into the following equation (7), respectively. The temperature ratio (Tr1) of the first stage impeller 22 is calculated. In addition, ft in this formula (7) means a predetermined function different from fρ.
Tr1 = ft (comp, P1, T1, H1, η1) (7)

Then, the inlet / outlet pressure ratio calculating means 143 calculates the pressure (P1) at the first stage impeller 22 and the pressure ratio (Pr1) of the first stage impeller 22 obtained by Expression (6), respectively by the following formulas (8 ), The pressure (P2) at the second stage impeller 22 is calculated. Further, the inlet / outlet pressure ratio calculating means 143 calculates the temperature (T1) at the first stage impeller 22 and the temperature ratio (Tr1) of the first stage impeller 22 obtained by the expression (7), respectively by the following formulas (9 ), The temperature (T2) at the second stage impeller 22 is calculated.
P2 = P1 × Pr1 Expression (8)
T2 = T1 × Tr1 (9)

Thereafter, the inlet / outlet pressure ratio calculating means 143 performs the calculation from the equations (1) to (9) for the impellers 22 of each stage. Then, the inlet / outlet pressure ratio calculating means 143 substitutes the pressure ratios Pr1, Pr2, Pr3,... Prz obtained for the impellers 22 of each stage into the following formula (10), thereby the centrifugal compressor 1 The inlet / outlet pressure ratio (Pr) is calculated.
Pr = Pr1 * Pr2 * Pr3 ... * Prz Formula (10)

  Next, as shown in FIG. 3, the performance determination means 144 shown in FIG. 2 determines whether or not the calculated inlet / outlet pressure ratio (Pr) satisfies the required performance (S5). As a result, when it is determined that the centrifugal compressor 1 does not satisfy the required performance (S5: No), the process returns to S3 and the structural specifications of the impeller 22 and the rotational speed (N) of the centrifugal compressor 1 are determined again. Then, the process of determining whether or not the required performance is satisfied by calculating the inlet / outlet pressure ratio (Pr) is repeated. On the other hand, if it is determined in S5 that the centrifugal compressor 1 satisfies the required performance (S5: Yes), the process proceeds to S6.

  Here, when returning from S5 to S3 and re-determining the structural specifications of the impeller 22 and the number of revolutions (N) of the centrifugal compressor 1, the order of the impeller 22 of each stage, The outer diameter (D2i) of the impeller 22 of the stage, the rotation speed (N) of the centrifugal compressor 1, and the number of stages (Z) of the impeller 22 are set in this order.

  Subsequently, in the control unit 14 shown in FIG. 2, a shaft natural frequency calculation step is executed. This shaft natural vibration calculating step is a step of calculating the natural frequency of the rotating shaft 21 from the drawn CAD drawing.

  The shaft natural frequency calculation step will be described in detail. First, the CAD drawing means 145 shown in FIG. 2 arranges the impellers 22 of the respective stages whose structural specifications are determined as described above along the rotary shaft 21, thereby providing CAD. The drawing is drawn (S6).

  Next, the shaft natural frequency calculation means 146 shown in FIG. 2 measures the dimensions of each part based on the drawn CAD drawing. Based on the measurement result, the shaft natural frequency calculating means 146 calculates the shaft natural frequency of the rotating shaft 21 (S7).

  In the present embodiment, the CAD drawing unit 145 executes CAD drawing (S6), and the shaft natural frequency calculation unit 146 executes calculation of the shaft natural frequency (S7). However, regarding the processes of S6 and S7, instead of such automatic execution, the calculation is performed manually by the user based on the structural specifications determined to satisfy the performance by the performance determination unit 144. The shaft natural frequency may be input.

  Subsequently, in the control unit 14 illustrated in FIG. 2, a resonance determination step is executed. This resonance determination step is a step of determining whether or not the rotation shaft 21 resonates based on the shaft natural frequency of the rotation shaft 21 and the rotation speed (N) of the centrifugal compressor 1.

The resonance determination step will be described in detail. The resonance determination unit 147 shown in FIG. 2 includes the shaft natural frequency calculated by the shaft natural frequency calculation unit 146 and the rotation speed of the centrifugal compressor 1 determined by the structural specification determination unit 142. It is determined whether or not the rotating shaft 21 resonates by determining whether (N) satisfies the following expression (11) (S8). Here, α means SM (Separation Margin) defined in API (American Petroleum Institute) 617 standard 2.6.2.
| Shaft natural frequency / rotation number -1 |> α Equation (11)

  If it is determined in S8 that the rotating shaft 21 does not resonate (S8: No), the CAD drawing means 145 shown in FIG. 2 outputs the CAD drawing data to the display unit 13, and then the process ends.

  On the other hand, in the determination in S8, when it is determined that the rotating shaft 21 resonates (S8: Yes), it is determined whether or not the number of times that the resonance determination number counting means 148 shown in FIG. Determine (S9). As a result, when it is determined that the number of resonance determinations has not reached the nth time (S9: No), the process returns to S3 and the structural specifications of the impeller 22 and the rotational speed (N) of the centrifugal compressor 1 are determined again. Thereafter, the subsequent processing is repeated.

  On the other hand, if it is determined that the number of times that the resonance determination has been made in the determination in S9 has reached the nth time (S9: Yes), the number of times that the boss ratio change frequency counting means 149 shown in FIG. It is determined whether or not the m-th time has been reached (S10).

  Then, as a result of the determination in S10, when the boss ratio change count counting means 149 determines that the number of times of changing the boss ratio has not reached the mth (S10: No), the boss ratio change means shown in FIG. 150 changes the boss ratio from the initial value (S11). More specifically, as shown in FIGS. 5A and 5B, the initial value of the boss ratio is set to the lowest boss ratio (shown by a solid line). The boss ratio changing means 150 sets the boss ratio to the lowest boss ratio as shown by a two-dot chain line in FIG. 5 within a boss ratio setting range predetermined as a range from the lowest boss ratio to the highest boss ratio (shown by a broken line). Set to a slightly higher value.

  The initial value of the boss ratio is not limited to the minimum boss ratio as in this embodiment, and can be set to an arbitrary value within the boss ratio setting range. However, if the initial value is set to the lowest boss ratio as in the present embodiment, the boss ratio can be minimized at the initial design time, and a higher performance centrifugal compressor 1 can be designed. When it is not possible to prevent resonance, it is possible to secure a sufficiently large change width of the boss ratio, so that it is possible to easily select a condition that does not cause resonance within a range that satisfies the performance. Become.

  Thereafter, returning to S3 in FIG. 4, the structural specifications including the boss diameter Db (see FIG. 1) on the inner peripheral side of the blade 222 without changing the structure of the blade 222 for the impeller 22 whose boss ratio has been changed. By changing, the impeller 22 is set to the changed boss ratio. As a result, since the blade 222 that requires time and cost for development is not changed, the centrifugal compressor 1 that satisfies the required performance and does not cause resonance of the rotating shaft 21 is designed in a short time and at low cost. can do.

  Thereafter, the processes after S4 are repeated. At this time, in order to calculate the inlet / outlet pressure ratio (Pr) in S4, the efficiency (ηi) and pressure coefficient (μi) of the centrifugal compressor 1 corresponding to the changed boss ratio are determined using FIG. In this case, the interpolation may be performed using the curve of the lowest boss ratio and the curve of the highest boss ratio.

  On the other hand, as a result of the determination in S10, when the boss ratio change frequency counting means 149 determines that the number of times of changing the boss ratio has reached the mth (S10: Yes), the shaft casing dividing means shown in FIG. 151 divides the rotating shaft 21 and the casing 3 into a plurality of pieces (S12). Thereafter, the process returns to S3 in FIG. 4 and after re-determining the structural specifications of the impeller 22 and the rotational speed (N) of the centrifugal compressor 1, the processes after S4 are performed until it is determined in S8 that the rotating shaft 21 does not resonate. repeat.

  Or, as a result of the determination in S10, when the boss ratio change frequency counting means 149 determines that the number of times of changing the boss ratio has reached the mth (S10: Yes), the new impeller development means shown in FIG. 152 newly develops the impeller 22 having a new shape. More specifically, when a boss ratio larger than the maximum boss ratio graph shown in FIG. 5 is required, the new impeller development means 152 develops a new impeller 22 by modifying the shape of the blade 222 (S12). ). Thereafter, the process returns to S3 in FIG. 4 and after re-determining the structural specifications of the new impeller 22 and the rotational speed (N) of the centrifugal compressor 1, until S8 determines that the rotary shaft 21 does not resonate, Repeat the process.

  After performing the design process by the above design method, the centrifugal compressor 1 having the structural specifications designed in the design process is manufactured. Specifically, the method includes a member manufacturing process for manufacturing each member of the centrifugal compressor 1 that satisfies the above structural specifications, and a member assembly process for assembling the members manufactured in the member manufacturing process.

  Each member manufactured in the member manufacturing process is each member shown in FIG. 1, for example, the rotating shaft 21, the impeller 22, the casing 3, and a bearing. The rotary shaft 21 is manufactured, for example, by cutting a steel material made of a predetermined material. Further, the impeller 22 may be manufactured by assembling and assembling the disk 221, the blade 222, and the shroud as separate bodies, or may be manufactured integrally.

  When manufacturing each said part of the impeller 22 as a different body, after manufacturing the mother die corresponding to each shape by forging, casting, etc., it is manufactured by finishing the details by cutting or the like. At this time, for example, the disk 221, the blade 222, and the shroud are not all manufactured separately, but the disk 221 and the blade 222 or the blade 222 and the shroud may be manufactured integrally. And each manufactured part is manufactured as the impeller 22 by joining by welding, brazing, etc. Further, in the case of manufacturing integrally, after forming a mother die corresponding to the shape of the impeller 22 by forging, casting or the like, the portion to be the flow path 4 is formed by cutting by mechanical cutting or electric discharge machining. .

  The casing 3 is formed by casting or the like. In assembly, it is divided into two parts so as to be half-cracked, and is integrally assembled in the following member assembly process.

  In the member assembling step, for example, the impeller 22 is first assembled to the rotating shaft 21 so as to be integrated by shrink fitting. Further, bearings are assembled to both ends of the rotating shaft 21. Next, the rotating shaft 21, the impeller 22, and the bearing that are integrated are assembled in one half of the casing 3. Finally, it is completed by assembling the other side of the casing 3 to one side.

  As described above, according to the design system of the centrifugal compressor 1 according to the present embodiment, the boss diameter on the inner peripheral side of the blade 222 without changing the structure of the blade 222 for the impeller 22 whose boss ratio is changed. By changing the structural specification including Db (see FIG. 1), the impeller 22 is set to the changed boss ratio. As a result, since the blade 222 that requires time and cost for development is not changed, the centrifugal compressor 1 that satisfies the required performance and does not cause resonance of the rotating shaft 21 is designed in a short time and at low cost. can do.

  In addition, the member manufacturing process and the member assembling process show a manufacturing process of a general compressor, and other members constituting various structures such as a seal structure and an intake structure are manufactured in the member manufacturing process. It is assembled in the member assembly process.

  The centrifugal rotating machine according to the present invention is not limited to the centrifugal compressor 1 described in the present embodiment, and may be a centrifugal pump or the like.

  Further, instead of the design system executing all the processes described above, the user may perform the process manually.

  The various shapes, combinations, operation procedures, and the like of the constituent members shown in the above-described embodiments are merely examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Centrifugal compressor 2 Rotor 3 Casing 4 Flow path 11 Memory | storage part 12 Input part 13 Display part 14 Control part 141 Compressor type determination means 142 Structural specification determination means 143 Entrance / exit pressure ratio calculation means 144 Performance determination means 145 CAD drawing means 146 Axis Natural frequency calculation means 147 Resonance determination means 148 Resonance determination frequency count means 149 Boss ratio change frequency count means 150 Boss ratio change means 151 Shaft casing dividing means 152 New impeller development means 21 Rotating shaft 22 Impeller 221 Disc 222 Blade 221a Boss portion 31 Casing body 32 Thrust bearing 33 Journal bearing 34 Bearing case 35 Bearing case Db Boss diameter D2 Impeller outer diameter L Axis T Table

Claims (6)

A design method of a centrifugal rotating machine provided with a rotating shaft and a plurality of impellers provided in the rotating shaft along the axial direction,
A structural specification determination step for determining the structural specifications including the impeller type of each stage in the centrifugal rotating machine and the rotational speed of the centrifugal rotating machine so as to satisfy the weight flow rate and the inlet / outlet pressure ratio acquired in advance;
A shaft natural frequency calculating step for calculating the shaft natural frequency of the centrifugal rotating machine in the structural specification determined in the structural specification determining step;
Resonance determination step for determining whether or not to resonate based on the shaft natural frequency of the centrifugal rotator calculated in the shaft natural frequency calculation step and the centrifugal rotator rotation speed determined in the structural specification determination step When,
When it is determined that the resonance is determined in the resonance determination step, a boss ratio which is a value obtained by dividing the minimum diameter of the disk constituting the impeller by the maximum diameter of the disk with respect to at least one stage of the impeller is a model of the impeller The boss ratio changing step for setting a value higher than the initial value in the boss ratio setting range obtained in advance corresponding to
Including
When the boss ratio is set in the boss ratio changing step, the inner circumference of the impeller having the boss ratio set in the structural specification determining step is changed more than the inner circumference without changing the structure of the blade constituting the impeller. The centrifugal structure is characterized by changing the structure on the side to change the structure to the boss ratio, determining the structural specifications and the rotational speed of the centrifugal rotator again, and executing the natural frequency calculation step and the resonance determination step. How to design a rotating machine. The method for designing a centrifugal rotating machine according to claim 1, wherein the structural specification determined in the structural specification determining step further includes the number of stages of the impeller and the maximum diameter of the disk of each stage.   The method for designing a centrifugal rotator according to claim 1 or 2, wherein the boss ratio changing step is executed when it is determined that the resonance determining step is repeated a predetermined number of times to resonate. .   In the structural specification determining step, an initial value of the boss ratio is set to a minimum boss ratio, and the boss ratio setting range in the boss ratio changing step is a range from the minimum boss ratio to a predetermined maximum boss ratio. The design method of the centrifugal rotating machine according to any one of claims 1 to 3, wherein the design method is defined. A design process for designing the structure of the centrifugal rotator by the centrifugal rotator design method according to any one of claims 1 to 4,
Each centrifugal rotator including a rotating shaft in the centrifugal rotating machine, an impeller attached to the rotating shaft, and a casing that rotatably supports the rotating shaft while accommodating the impeller with the structural specifications designed in the design process A member manufacturing process for manufacturing a member;
And a member assembling step of assembling the centrifugal rotator member manufactured in the member manufacturing step. Structural specification determining means for determining the structural specifications including the impeller type of each stage in the centrifugal rotating machine and the rotational speed of the centrifugal rotating machine so as to satisfy the weight flow rate and the inlet / outlet pressure ratio acquired in advance,
Judgment whether or not to resonate based on the shaft natural frequency of the centrifugal rotator calculated from the structural specification determined by the structural specification determining means and the centrifugal rotator rotational speed determined by the structural specification determining means Resonance determining means for
When it is determined that the resonance is determined by the resonance determining means, the disk of the disk constituting the impeller is within the boss ratio setting range obtained in advance corresponding to the type of the impeller for at least one stage of the impeller. A boss ratio changing means for setting the boss ratio, which is a value obtained by dividing the minimum diameter by the maximum diameter of the disk, to a value higher than the initial value, and outputting to the structure specification determining means
With
When the boss ratio is output from the boss ratio changing means, the structural specification determining means is configured so that the impeller for which the boss ratio is set does not change the structure of the blade that constitutes the impeller, and does not change the inner structure of the impeller. The structure on the peripheral side is changed to change the structure to the boss ratio, the structure specification and the centrifugal rotator rotational speed are determined again, and the resonance determining means determines whether or not to resonate again. A design system for centrifugal rotators.

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